Number-indicating system



Get. 30, 1923.

E. H. CLARK NUMBER INDICATING SYSTEM mm QE mm: ON. @2 09 mmw mhb $10 0 930M 9 O 4 Sheets-Shut k M van far. faqm" f7. C/a/"A' Filed Dec. 25

E. H. CLARK NUMBER INDICATING SYSTEM Filed Dee. 26 1919 4, Sheets-Shem 5 WWW?! Edgar H C/ar/r' Y E. H. CLARK NUMBER INDIGATING SYSTEM Filed Dec. 26 1919 4 Sheets-Shet 4 Anya/17%; faqar f7! Clark Patented oa. so, 1923.

EDGAR H. CLARK, OF RICHMOND HILL, NEW YORK, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A COREORATION OF NEW YORK.

NUMBER-INDICATING SYSTEEI.

Application filed December 36, 1919. Serial No. M7510.

To all whom it may concern:

Be it known 'that I, EDGAR H. CLARK, a

citizen of the United States, residing at' Richmond Hill, in the county of Queens,

State of New York, have invented certain new and useful Improvements in Number- Indicating. Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to number indicato ing systems and more particularly to number indicating systems adapted for use in automatic telephone exchange systems.

It is the object of this invention to provide means such that thev position assumed by a selective device ofany type may control a number indicating device to register a numeral corresponding to the particular position whichsuch device has assumed.

It is a further object of this invention to so provide means such that in case a number of switching devices have access to a group of lines which are consecutively numbered, and in case such group of lines is divided into a number of sub oups each consecutively numbered within certain numerical limits, a number indication may be produced which will. indicate which line of the main group has been seized, this number indication being determined in accordance with which switch was operated and in accordance with the position assumed. by such switch. A A feature of the invention is an arrangement such that the position taken, by the selecting device sets up certain conditions by'means of certain contacts controlled by it so that the proper number indication may be controlled in accordance with' such setting.

It is an additional feature of the invention to provide means, individual to each group of lines served by a switching device, to position corresponding controlling devices so that the display of the number will not only convey information in regard tothe number of the line in the selected group, but will also convey the complete number as determined by the group and the particular line in the group selected.- It is obvious so that if each switching device had access to merely tenlines, this designation would be readily accomplished, but when a switching device serves lines which are. greater or less in number than ten, the required translaindicated at123, 124 and 125.

tion introduces difficulties which it is the purpose of this invention to overcome.

The invention has been applied to, and the circuits as shown are arranged to cooperate with, the system shown in application serial No. 301,891, filed June 5, 1919 by A. E.

Lundell and E. H. Clark. The scope of dividual to each group of trunks leading to mechanical ofiices similar to the oilice Fig. 2, which is to be placed to the right of Fig. 1 shows circuit controlling equipment common to the various operatorsin the exchange. In the lower left-hand portion of this figure is indicated an operators finder switch of the type disclosed in the above-mentioned application. To the right of the vertical dotted line are shown the circuits of a finder and impulse sending switch which operates in conjunction with the .trunk selector switch whose circuits occupy the remainder of the drawing. Fig. 3, which is to be placed below Fig. 1,'shows the operators controlling key set and a portion of the controlling relays for the number indicating device. Fig. 4,.which is to be placed to the right of Fig. 3, shows the number in-.

dicating lamps and certain other controlling relays therefor.

Since the invention is concerned only with the number indicating feature, the complete operation of the system will not be de:

scribed. Itv is to be understood that appa-' ratus and circuits not shown are identical with those shown in the above-mentioned application and it is to be understood that ice in the above-mentioned application. Alike system of numbering has been. employed so far as possible in QI'der that the relation of the present system to that shown in the above-mentioned application may be more readily understood. Y

In accordance with the general organization of the system in connection with which this invention has been shown, trunks terminating at the manual exchange are divided into grou s, each group of trunks leading to a particu ar mechanical exchange and there connecting with selectively operable switching devices to be termed incomlng selector switches. Each operator at the manual exchan e is provided with a set of keys on whic the wanted number may be registered, and an indicator for thedisplay of the designation of the mechanical exchange and the trunk chosen for. the extension of a call.

There is provided, for the common use of all operators a group of connecting units for each of the groups of trunks leading to a mechanical exchange and a group of registering and controlling equipments accessible to all operators through the medium of any one of said connecting units. Each connectin unit consists of three automatic switchin mechanisms. One of these mechanisms will be termed an operators finder switch and is provided for the purpose of associating the key-set and indicating equipment of any operator with the connecting unit. A second mechanism that will be termed a trunk selector is provided for the purpose of associating the connectin unit with an idle trunk of the group leading to the desired mechanical exchange, and a third mechanism (not shown) that will be termed a sender selector is for the purpose of associating an idle registering and controlling equipment or sender with the connecting unit. All of the senders are'accessible to any one of said connecting units.

An allotting and controlling mechanism (not shown) is provided for each group of connectin units. This mechanism consists of an exe ange keyfor each mechanical exchange at each operators position, and an allotter switch controlled by any one of the associated exchange keys to allot an idle connecting unit for the use of the operator desiring a connection to the corresponding mechanical exchange.

The manual operator, in extending a call to a subscriber in a mechanical exchange makes use of the ordinary manual cord circuit in combination with one of these connecting units. The operator ascertains the wanted number from the calling subscriber andv then associates the keys and the trunk'indicator with an idle connecting unit having access to a group of trunks leading to the desired exchange. The connecting unit is also automatically connected to an idle sender. The finding of an idle trunk leading to the wanted exchange and the indicating of the number of the chosen trunk 1 ,a'raaw selector switches at the mechanical ofiice, the

operator connects the outgoing end of the cord circuit associated with the calling subscribers line, with the selected trunk, and when the selective operations at the mechanical exchange are completed, the wanted subscriber is signaled in the usual manner and the connecting unit is released and made accessible for a second call.

The selector switches at the mechanical exchange and their operating circuits are power driven switches of the well-known type and need not be described.

The various switches shown in the drawing are of the well-known step-by-step type in which a stepping pawl operates a ratchet wheel to which are connected brushes or wipers adapted to travel over the contacts of an arcuate terminal bank. These brushes or wipers are so arranged that for each step of the operating magnet the brushes or wipers engage a corresponding set of terminals. The operators finder switch 300 is equipped with eight brushes and corresponding-terminal banks, while the selector switch 400 is equipped with six brushes and corresponding terminal banks and the impulse switch 600 is equipped with five brushes and corresponding terminal banks. Switches 300 and 400 have no normal positions but stop in whatever position they are placed by their respective operating magnets. Each of these switches is arranged to have twenty terminals in a bank. The switch 600 does have a normal position-and need have only seven-terminals in a bank. The trunk indicator consists of three series of ordinary switchboard lamps arranged to indicate the hundreds, tens and units digits. The detailed operation of the system is as follows.

When the subscriber at station 200 removes his receiver from the switchhook the line relay 202 energizes and lights the lamp 203 by means of a circuit through its arma: ture and front contact. On receiving this signal, the operator inserts plug 295 into jack 296 closing a circuit for cut-off relay 297 to extinguish the lamp 203. The operator then mani ulates listening key 209 to connect her te ephone set 211 to the subscribers line in the usual manner.

The operator, after receiving the wanted number from the subscriber at station 200, depresses the exchange key 114 bearing the -trunkindi'cator relays for a purpose which will appear hereinafter. Relay 205 closes a circuit at its outer right-hand iront contact and armature, for .the exchange lamps 208 that indicate to the operator the exchange for which the call is intended. Relay 205 also completes a circuit extending from ground over conductor 238, to put into operation an allotted controlling unit. This contro ling unit when once put into operation functions as described-in the above mentioned application to cause trunk selector 400 to advance until its brushes come to rest on the terminals of an idle trunk leading to the desired office, and at the sam'e time cause operators finder switch 300 to connect the operators key set to an idle sender which is at the same time selected by means of a sender, selector (not shown). The advance of selector switch 400 is under the control of stepping magnet 416 and the advance of finder 300 is under the control of stepping magnet 308 as is fully described in the above mentioned application. 7

As soon as the connecting unit is operated to connect the key set 113 to an idle sender, dialing tone is conveyed to the operator over conductor 334 through the inductive windings of coil 223 and thence by way of the outer left-hand armature and contact of relay 205 to ground through a winding or the induction coil of the operators telephone set 211. This dialing tone indicates to the operator that an idle sender has been connected to the keys 113. The setting up of the wanted number on the keys 113 may now be begun, regardless of whether or not the trunk selector has found an idle trunk. Since the present invention is not concerned with the eneral operation of the system it has not een considered necessary to describe the manner in which keys 113 operate to control registration in the sender. As soon as trunk selector 400 has found an idle trunk, relay 505 is energized and completes the fundamental circuit 447 and 448 through its left-hand armatures and front contacts by connecting it to the outgoing trunk leads 507 and 508. Relay 505 completes a circuit from grounded battery, outer right-hand armature and contact of relay 505, winding of relay 509 to ground, thus causing the energization of relay 509.

Relay 509 is individual to the group of trunks leading to the desired ofiice' bince trunk selector 400 has access to twenty terminals, the relay 509 must control the designationof the particular group of 20 in which the trunk selected occurs. The trunk indicator is shown as arranged to have acapacity to provide" indications for an operators position equipped with 160 trunks. If, then, there are twenty trunks leading to each mechanical ofiice, there will be eight sets of switches corresponding to trunk selector 400, and there will be a relay corresponding to 509, these relays being indicated in Fig. 1. by the designations 510 to 516 inclusive, individual to each such group of trunks. It is therefore obvious that if an operator depresses some other ofiice key, some other trunk selector switch corresponding to switch 400 would have been put into operation and that some other one of the relays 510 to 516 inclusive would have been energized when the relay corresponding to relay 505 became energized.

this particular type of arrangement since it is readily conceivable that it would be desirable to have more than twenty trunks running to a particular mechanical office. In this case, since each trunk selector has access to only twenty trunks, it might be necessary to provide a number of trunk selector switches for each connecting unit. The operation of these switches would be such, that, provided all the trunks of the first group were busy, a circuit, which in efiect would be an extended starter-wire, would cause a sec- .ond switch having-access to twenty trunks, numbered from 20 to 39, would be started. and if allthese trunks were busy a third switch, having access to trunks numbered from 40 to 59. might be'started. In case of an arrangement of this kind, there-would have to be a relay corresponding to relay 509 individual to each group of trunks and the operation of the indicator in recording the number of the trunk selection would be the same as will now be described.

It will be assumed that the switch 400,

Obviously the invention is not limited to shown in Fig. 2 has access to twenty trunks and that these trunks are in the third twenty appearing at the operators position, and are therefore numbered from 40 to 59. It will further be assumed that the trunk selected is the last trunk in the group and is therefore sition, conductor 602, brush 344 and its associate contact, conductor 343, inner righthand armature and back contact of relay 250, winding of relay 251, conductor 252', right-hand winding of relay 253 to battery and ground. Since ground through no resistance is supplied at the armature and contact of relay 509, marginal relay 253 is energized in this circuit, as are also sensitive relays 251 and 461. Relays 461 and 251 would have been energized even though a'resistance had been included in the path to ground at the contact of relay 509. Relay 253, upon energization locks up-through its left-hand winding and left-hand armature and front contact to conductor 254 which is grounded at the armature and contact of relay 207 as previously described. Relay 253 at its righthand armature and front contact completes an energizing circuit for relay 282. The

- left-hand armature of relay 509 completes a circuit from ground, left-hand armature and contact of relay 509, conductor 551, lefthand winding of relay 461, brush 603 in its nOIIIlfllPOSllZlOIl, conductor 604, brush 341, conductor 340, left-hand armature and back contact of relay 250, winding of rela 255,

, conductor 256, right-hand winding 0 marginal relay 257 to battery and ground. Since direct ground is supplied at the left-hand armature of relay 509, marginal relay 257 is energized. Relay 255 is also energized in this circuit. It is to be noted at this point that current flow through either of the windings of the relay 461, whether through a resistance at contacts of relay 509 or directly to ground, would have allowed suflicient current flow-to energize relay 461. Marginal relay 257 locks up through its left-hand winding and inner left-hand armature and front contact to grounded conductor 254. Relay 257 at its outer right-hand armature and contact completes a circuit for relay 268. Belay 268 is energized and remains energized until relay 257 deenergizes.

Relay 461 upon energization completes a circuit from grounded'battery', winding'of relay 460, left-hand armature and front contact of relay 461 to ground. Relay 460 upon energization locks up through its inner right-hand armature and contact to ground at outer right-hand armature and back contact of relay 453. Relay 461 upon energiza tion also locks up through its right-hand winding independently of relay 460 by way of its right-hand armature and contact.

Referring now to Fig. 3, it is to be observed that the energization of relay 251 completes a circuit from ground, armature and contact of relay 251 conductor 258, winding of relay 259 to grounded bat- Relay 259 is energized in this circuit te arid locks up throughits inner right-hand y armature and contact 'toconductor 254. Similarly the energization of'relay 255 completes a circuit from ground, armature and contact of relay 255, conductor 260, winding of relay 261 to battery and ground. Relay 261 is energized'and locks up over'its left-hand armature and contact to grounded conductor 254. As soon as eitherrelay 259 or relay 261 is energized a circuit is completed from grounded battery, winding of relay 250, conductor 262, to ground ateither the outer right-hand armature and contact of relay 261 or the outer left-hand armature and contact of relay 259. Relay 250 is energized and connects the controlling leads 340 and 343 to conductors 263 and 264 respectively, thus opening the circuits through both windings of relay 461, and allowing this relay to deenergize. Relay 250 upon energization also completes a circuit from grounded battery, winding of relay 265, outer right-hand armature and contact of relay 250 to ground. Relay 265 is energized and connects the controlling leads 263 and 2 64 1to controlling leads 266 and 267 respective y.

Regardless of what potential combinations may be found on leads 266-and 267, the interval before the energization of relay 265 is sufficient to allow relay 461 to deenergize when relay 250 opens leads 340 and 343. The deenergization of relay 461 completes a circuit from grounded battery, stepping magnet 605 of the switch 600, armature and back contact of magnet 605, armature and back contact of relay 606, brush 607 and its normal contact, outer right-hand armature and contact of relay 460, left-hand armature and back contact of relay 461 to ground. Magnet 605 is energized and interrupts its own circuit to cause the advance of switch 600 into its second position.

It istobe observed at this point that as soon as the operators finder switch 300 was positioned and relay 320 was energized, by means of circuits which it has not been considered necessary to describe in the present application, a circuit was completed from grounded battery, right-hand winding of relay 466, left-hand winding of relay 467, switch arm 468, which is resting on its 20th contact, conductor 469, armature and contact of relay 320 to ground. Relays 466 and 467 are both energized in this circuit. Relay 466 is energized whenever the trunk selected is in the second five of a given tens group. Relay 467 is energized whenever the trunk is in the second ten of the given twenty. Since trunk number 19 in this particular group of trunks has been selected and since this is a trunk in the second fiveof the second ten, both relays 466 and 467 are energized to control the proper registrations upon the lamp controlling relays.

With switch arm 603 in engagement with its second contact a circuit is completed contact, conductor 340, left-hand armature and front contact of. relay 250, conductor 263, left-hand armature and contact of relay 265, conductor 266, left-hand armature and back contact of relay 269, conductor 270,

left-hand winding of marginal relay 271 to ground. Relays 453 and 271 are energized in this circuit and relay 271 looks up over its right-hand winding and right-hand armature and contact to grounded conductor 254. It is to be observed that if the line selected had not been in the second ten,

' relay 467 would not have been energized.

The circuit of relay 453 would then have extended by way of a resistance 471 to conductor 470. The completion of this circuit would have allowed relay 453 to be energized but in this case relay 271 would not have been energized.

- The energization of relay 453 opens the locking circuit of relay 460 and this relay deenergizes. At its inner right-handarmature and front contact relay 453 completes a circuit from grounded battery, winding of magnet 605, armature and back contact of such magnet, armature and back contact of relay 606, brush 607 and its second contact, inner right-hand armature and front contact of relay 453 to ground. Magnet 605 is energized and interrupts its own circuit to advance the various brushes of switch 600 into engagement with their third contacts respectively.

, As soon as brush 601 en ages its third contact, a circuit isv complete from ground, armature and front contact of relay 466, conductors 472 and 473, brush 601 and its third contact, conductor 602, brush 344 and its associated contact, conductor 343, inner right-hand armature and front contact of relay 250, conductor 264, right-hand armature and contact of relay 265, winding of sensitive. relay 272, conductor 273, righthand winding of marginal relay 274 to grounded battery. Marginal relay 274 and relay 272. are energized in this circuit. It is to be observed that had the line selected been in the first five of either the first or second ten of the trunk group, relay 466 would not have been energized. As a result the circuit extending from rounded battery, through relays 274 and 2 2 would have been extended to ground through a resistance 474. The presence of this resistance would have prevented the energization of relay 274. Relay 272 would, however, have been energized as just described.

At its right-hand armature rela 272 completes a circuit from ounde battery, winding of relay 269, left-hand armature and back contact of relay 277, conductor 278, right-hand contact and armature of relay 272 to ground. Relay 269 is energized in this circuit and repares a locking circuit for itself through its right-hand armature and contact and through the winding of relay 277. This circuit, however, does not become effective to allow relay 277 to be energized until relay 272 is deenergized. The energization of relay 269 does, however, open the circuit of relay 453 which relay was maintained energized in the third position of switch 600 over its original energizing circuit. When the circuit of'relay 453 is opened this relay deenergizes and completes a circuit from grounded battery, winding of magnet 605, armature and contact of magnet 605, armature and contact of relay 606, brush 607 and its third contact, inner right-hand armature and back contact of relay 453 to ground. Magnet 605 is energized and interrupts its ownv circuit to advance the brushes of switch 600 into engagement with their fourth contacts respectively.

" As soon as brush 601 leaves its third con tact the circuit of relays 272 and 274 is opened. Relay 274 is maintainedenergized due to the fact that upon energization it was locked up through its left-hand winding and left-hand armature and contact to grounded conductor 254. Relay 272, however, deenergizes and allows relay 277 to operate in the manner usual: for countin relays. With relay 277 ener "zed a circu1t is completed from ground, 1e t-hand armature and back contact ofcounting relay 279, inner right-hand armature and front contact of relay 277, left-hand armature and front contact of relay 269, conductor 266, thence over a previously described circuit to batdifference being that this circuit now extends by way of the fifth contact of brush 601 instead of by Way of the third contact of such brush. Relay 272 is energized and at its right-hand armature completes a-circuit from grounded battery, winding of relay 279, left-hand armature and back con tact of relay 280, left-hand armature and ,front contact of relay 277, conductor 27 8. to

ground. Relay 279 is energized and prepares a circuit for relay 280. It is to be noted that relay 272 operates asa steppin relay to control the successive actuation o the counting relay group comprising relays 269, 277, 279, 280 and 281.

Relay 279 at its left-hand armature opens the energizing circuit for relay 453 and this relay deenergizes to cause stepping magnet 605 to advance the brushes of switch 600 into engagement with their sixth terminals r ective y.

soon as brush 601 leaves its fifth contact relay 272 is deenergized and allows relay 280 to become energized and lock up in series with relay 279 to grounded conductor 254. Relay 280 at its inner right-hand armature and front contact completes a circuit from ground over the left-hand armature and back contact of relay 281, inner right-hand armature and front contact of relay 280, left-hand armature and front contact of relay 279 inner ri ht-hand armature and front contact of re ay 2'77, left-hand armature and front contact of relay 269 to conductor 266 to gtrounded battery through the winding of relay 453. Relay 453 is energized and completes a circuit for stepping magnet 605 to advance switch 600 into its seventh position. When brush 601 engages its seventh terminal relay 272* is energized to cause the energization of relay 281. Relay. 281 is energized and locks up over its inner right-hand armature and front contact be grounded conductor 254 and at its left-hand armature removes the holding ground for relay 453. Relay 453 deenergizes, but does not cause switch 600 to move out of position 7 since the circuit of stepping magnet 605 is open at the righthand armature and contact of relay 606 which was energized as soon as brush 608 engaged its seventh contact, due to the closure of a circuit from grounded battery, winding of relay 606, brush 608 and its associated contact, brush 480, which is in engagement with the twentieth terminal in the are served by it, to ground.

It is to be observed that had switch 400 seized trunk No. 15 in the third group, brush 480 would have been in engagement with its sixteenth terminal and therefore switch 600 would have been brought to rest with its brushes in engagement with their third terminals respectively. In this case relay 269 would have been the only one of the counting relays in Fig. 4 to have been ener 'zed. It-i's therefore apparent that in positions 1 to 3 of switch 600, impulses are sent to control the selection of the proper twenty group, the proper ten group and the proper five group and that thereafter the extent of motion of switch 600 determines which one of a particular five shall be indicated. Relay 606 operates as a test. magnet, as switch 600 is advanced due to the alternate energization and deenergization of relay 453 in the successive positions of switch 600.

As soon as relay 606 is energized a circuit is completed from grounded battery, winding of relay 206, conductor 284, brush 390 and its associated contact, conductor 609,

left-hand armature and contact of relay ground is supplied to control the lighting of the various indicatin lamps. Since the trunk selected is N o. 59, t e No. 0 lamp in the hundreds grou the N o. 5 lamp in the tens group and the o. 9 lamp in the units roup -must be lighted. The circuit for the o. 0

hundreds lamp extends from grounded battery, right-hand armature and front contact of relay 268, lamp No. 0, conductor 283, right-hand armature and front contact of relay 206 to ground. The circuit of the No. 5 tens lamp extends from grounded battery, left-hand armature and front contact of relay 271, through the No. 5 lamp,

left-hand armature and front contact of relay 282, outer left-hand armature and front contact of relay 257, inner left-hand armature and front contact of relay 259, inner.

right-hand armature and front contact of relay 261 to grounded conductor 283. The circuit of the No. 9 lamp in the units group extends from grounded battery, righthand armature and front contact of relay 274, through lamp No. 9, outer right-hand armature and front contact of relay 281, outer right-hand armature and front contact of relay 280, outer right-hand armature and front contact of relay 279, outer right-hand armature and front contact of relay 277, outer right-hand armature and front contact of relay 269 to grounded conductor 283. These lamps are now lighted to indicate to the operator the number of the jack which corresponds to the trunk which has been automatically selected. An inspection of the circuit arrangement in Fig. 4 will show that at this time no other lamps than those Whose circuits have just been traced can be lighted.

If the trunk selected had been trunk No. 55, switch 600 would have been brought to rest with its brushes in engagement with thelr third terminals, as previously stated,

and relay 269 would have been energized. As a result a circuit would have been comleted for the N o. 5 lamp in the units group. his circuit would have extended through .the outer right-hand armature and back contact of relay 277 and the outer righthand armature and front contact of relay 269 to grounded conductor 283.

Had the trunk selected been trunk No. 50, switch 600 would again have been brought to rest in its third position and relay 269 would have been the: only relay in the counting relay group to have been energized. However, 1n this case, relay 466,

which controls the five selection would not have been energized since the line selected is now in the first five of a given ten and therefore relay 274 would not have been energized with the result that when relay 206 was energized, a circuit would have been completed as is obvious for lamp No. 0 in the units group.

It is thought from the foregoing description the operation of the indicator in controlling the indication of any desired number may be readily understood.

As soon as the operator observes the lighting of the lamps 0, 5 and 9 in the hundreds, tens and units groups respectively, she will insert a plu 265 into jack 267 associated with trunk fio. 59. A circuit is thereupon completed from grounded battery, lamp266, sleeve contacts of plug 265 and jack 267, winding of slow release relay 520 to ground. Relay 520'is energized in this circuit and completes a circuit for slow release relay 502. Relay 502 is energized and establishes a locking circuit for itself through its inner right-hand armature and frontcontact. The operation of relay 502 causes the trunk indicator to be restored to normal by means of circuits which are started into operation by a circuit completed at the outer righthand armature and front contact of relay 502 by way of conductor 454. The ground supplled to conductor 454 operates to deenergize certain relays, not hown, but whose operation may be readily understood by reference to the above-mentioned application. The deenergization of these'relays removes the holding ground from the conductor 290 which has been maintaining relays 207 and 205 energized. As soon as this ground is removed, relays 205 and 207 are deenergized, since the original ground supply which caused the energization of these relays has been removed at the left-hand armature and back contact of relay 206, due to the energization of this relay. As soon as relay 207 deenergizes the locking circuits for the various lamp controlling relays are broken and all of these relays are deenergized. The deenergization of relay 207 also opens the circuit of the relay 610 which has been energized throughout the operation of the system. This relay was energized as soon as the operators finder switch 300 was positioned over a circuit extending from grounded battery, winding of relay 610, conductor 611, brush 391 and its associated contact, conductor 392 to grounded conductor 254. As soon as relay 610 deenergizes a cir cuit is completed from grounded battery, winding of stepping magnet 605, armature and back contact ofmagnet 605, armature and back contact of relay 606, which was deenergized as soon as switch 400 was restored to its normal position by means of circuits which it has not been considered necessary to disclose, brush 612 and its seventh contact, armature and back contact of relay 610 to ground. Magnet 605 is energized and continues to interrupt its own circuituntil the brush set has been, rotated through a complete cycle and back into its normal position at whichtime brush- 612 will fail to supply ground and the switch will be brought to rest.

All of the indicating apparatus has now been restored to its normal condition and -1s ready for reuse.

'means in accordance with which one of sai switching devices has been put into use and in accordance with the particular position assumed by said switching device.

2. be number indicatin system, selectively operable indicating evices, controlling means therefor, a plurality of multiposition switching devices, means to operate a desired one of said switching devices, an auxiliary switch, means to cause said auxiliary switch to assume a position determined by the position of said. operated switching device, and means to variabl operate said controlling means in accord ance with the positions assumed by said switching device and by said auxiliary switch.

3. In a number indicating system, indicat ing devices, controlling means therefor, a plurality of lines divided into major grou s, minor groups and subgroups, switching evices, means to operate one of said switching devices to seize a desired one of said lines, a

plurality of controlling relays, means to energize said relays in variable combination in accordance with the major group, minor group, and subgroup in which the selected line appears, and means to variably operate said controlling means in accordance with the condition of said controlling relays.

4. In a number indicating system, groups of lines, selectively operable indicating devices, controlling means therefor, a plurality of multiposition switching devices, means to operate a desired one of said switching devices to seize a desired line,and auxiliary switch, means to cause said auxiliary switch to assume a position determined by the setting of said switching device, means operative during the first portion of the movement of said auxiliary switch to variably operate said controlling means in accordance with group designations, and means to operate said controlling means during the final movement of said auxiliary switch to count off a number corresponding to the extent of travel of said switching device.

5. In a number indicating system, indicating devices, controlling means therefor comprising various relay combinations and a set of counting relays, a plurality of multiposition switching devices, means to operate a desired one of said switching devices, means to variably operate said relay combinations in accordance with which one of said switching devices has been put into use, and means to o erate said counting relay group in accor ance with a particular position assumed by said switching device.

6. In a number indicating system, indicating devices, controlling means therefor comprising various relay combinations and a set of counting relays, a plurality of multiposition switching devices, means to op-' erate a desired one of said switching devices, an auxiliary switch, means to set said auxiliary switch in a osition determined by the position assumed y said switching device, means to variably operate said relay combinations in accordance with which one of said switching devices has been put into use and in accordance with the position as sumed by said switching device, and means to operate said counting relay group in response to the advance of said auxiliary switch into a position determined by the position of said switching device.

7. In a number indicating system, indieating devices, controlling means therefor, a plurality of multi-position switching devices each provided with a lurality of brushes, a contact bank individual to each of said switching devices and arranged for engagement by said brushes, a plurality of lines I terminating in said contact banks, means to render a given line busy upon seizure by the. brush set of a switching device,'means to cause a desired one of said switching devices to hunt for an idle line, and circuits completed through certain ones of said brushes in the set position of said switching device for operating said controlling means to cause said indicating devices to register a number corresponding to the idle line seized by said switching dev1ce.

8. In a number indicating system, indieating devices, controlling means therefor a plurality of multi-position vswitching evices' each provided with a' plurality of brushes, a contact bank individual to each of said switching devices and arranged for engagement by said brushes, means to cause a desired switching device to select an idle contact set, means to thereupon render said contact set non-selectable by other switching devices, an auxiliary switch, and circuits completed through certain ones of said brushes in the set position of said switching device and dependent on the position as sumed by said auxiliary switch for operating said controlling means to cause said indicating devices to register a number corresponding to the number of the idle contact set selected.

In witness whereof, I hereunto subscribe my name this 19th day of December, A. D. 1919.

EDGAR H. CLARK. 

